362 On Meteoric Showers in August. 
posing that part of the world to be particularly favored in this re- 
spect. In fact these meteors are, according to scientific travelers, 
much more abundant within the tropics than in higher latitudes ; 
and Capt. Parry speaks of them as not uncommon in the extreme . 
north. This average number, however, appears to be the result of 
observations made before midnight, when of course shooting stars 
are least numerous, and also to be founded on the assumption, that 
* q single observer or several observers directed towards one and the 
same region,’ can detect half of the whole quantity visible at one 
place. This number is therefore too small. Observations made in 
this city, at various times in November, 1837, by three observers, 
(a number insufficient to secure all) give an average of rather more 
than 20 per hour.* Other observations justify the assumption of 
this number, as a fair hourly mean. During the entire day then, 
480 might be seen at one place if superior lights did not interfere. 
2. The distance at which shooting stars are ordinarily seen, I take 
at one hundred miles. A few may be seen at a greater distance, 
but very many more are probably invisible at fifty miles, and some, 
according to Quetelet, are discerned only by the telescope. Let 
this area be taken at 32,000 sq. miles. 3. The earth’s surface con- 
tains at least 196,800,000 sq. miles, and there are consequently upon 
it 6150 such areas. The Jatter number being multiplied into 480, 
we have 2,952,000 as the daily number for the whole earth. This 
is an average. ‘The actual number on any one day, (omitting the 
three yearly showers,) may be one fourth more or less than this. 
The source of these meteors must be of vast extent, to be able to 
sustain for thousands of years such incessant and enormous drafts. 
It seems not unreasonable to suppose, that, in a long course of time, 
the amount of matter resulting from the combustion of these meteors 
~ must be very considerable.t Some may ask whether, if these bodies 
meet the earth advancing in a direction opposed to their motion, they 
must not deprive it of some small portion at least of its projectile 
force, and thus shorten the year? Past observation answers in the 
* More observations on this point, in all parts of the world, at all times of the 
night and of the year, are much needed. Nine observers at one place are required 
to do full justice to the subject; yet four persons might probably see about three 
fourths of the whole visible number. 
+ Prof. Rafinesque’s ‘ Thoughts on Atmospheric Dust,” Vol. 1, p. 397 of this 
Journal, may be profitably consulted in this connection. See also Webster's 
Hist. of Epidemic and Pestilential Diseases, Vol. 2, p. 91. 
